Vacuum pump with expanding liquid spiral



March 3l, 1953 y H. G. scHAEFER ETAL l Iv2,633,290

VACUUM PUMP WITH EXPANDING LIQUID SPIRAL Filed May 13, 1950 Patented Mar. 31, 1953 VACUUM PUMP WITH LIQUID SPIRAL Henry G. Schaefer, Yonkers, and Philip Baumeister, Bronx, N .-Y.

Application May 13,- 1950, Serial No. 161,766 l Claims. (C1. 2-30108-) This invention relates to. vacuum` pumps and is intended primarily for use with steam heating systems, though the pump is. not limitedto such. uses.

The efficient. steam heating of. large structures demands the` use of mechanical means for evacuating the air from the piping system, and the best refinements in such heating systems involve the control of; the steam temperature by the regulation of: the. vacuum maintained within the piping, radiator and convector assembly, which tempera,- ture may be varied to. meet the heating needs in accordance with the; variations. in the outside temperature.

The. vacuum pumping equipment of the prior art. which hasbeen available for use with heatingv systems is dependent, almost. exclusively, on either mechanical or water jet Venturi evacuation. It is an object oi this invention to provide an improved vacuum pump that combines both kinds of evacuation,y and that uses the centrifugal force of a rotating jet for evacuating air from a chamber with which the piping of the. heating system communicates.

Some features of the invention relate to a vacuum pump construction in which. an impeller discharges a stream of Water into a discharge passageof substantially greater angular extent. than the water stream, andv in the preferred construction, the discharge passage is annular and. has top and bottomwalls that,Y converge toward. the outlet end of the. passage.

Another feature oi the invention relatesr tothe combination in such a pump of an impeller which dipsinto a supply ofA hurling water inthe bottom of the. pump and which is driven, by a motor lo.- cated` at an elevation. on top. of the pumpL This position of thev motor is particularly desirable WhenV the pump is located at.v a low place. a cellar, or other location thatmay at. times contain standing water. The high position of the. pump puts it at a safe distance above thefloor. and the water thatmay bestanding on the floor..

Another object of thev invention isV to provide an improved vacuum pump that hurls water throughV a discharge passage from a vacuum chamber into another chamber which is at atmospheric pressure and in which the Water separates from the air that is trapped between layers of.' Water during the operation of the pump. In this separation chamber the Water drains to the bottomand the invention provides a float. controlled valve for admitting the hurling Waterl back into the vacuum chamber.

Otherobjects, features and advantages. of the invention will appear or be pointed out as the description proceeds.

In the drawing, forming a part hereof, in which. like reference characters indicate corresponding parts in all' the vieWs,

is to beV evacuated. I-fhe inlet passage provided bythe pipe i2. isv preferably equipped with a check valve I-3 that opens. toward thev vacuum chamber;

The vessel I0 is surrounded. by a` housing I5. which. is substantially larger than the inner vessel. id so as to leave a chamber I'6`within the housing' I5:` and outside. of the cylindrical' vessel' II); This chamber I6 will. be referred to asA the separation chamber because air and'l Water discharged by` the vacuum. pump; separate in. this4 chamber I6, the water dropping. to the bottom of the chamber; The inner vessel IlIl and the outer vesselv or'ho'using I5 are connected to a common bottom WallL IT.

The housing I5. has a top I8- Which` also comprises the. topy for the cylindrical vessel IBL. and' there-is a iiange. 2.0i at theupper end of thevessel' Ill. This ange. 20T is spaced` from the inside' face of the top I8 and the confronting' faces of the top I8, and the. ange 20 converge toward the outer' edgefof the flange. The space between thetop I8 andthe ange ZI?. comprises an outlet passage' IL fromthe vacuum chamber I I.

Within the vessel HI' there is; an impell'er corniprising arotatableshaft'i? and" one or more pipes; 23' securedtothe shaft52`2 androtatable as a unit with the. shaft. The lower end of the shaft 2:2 turns. in. a thrustY bearing 26` held in the' bottom of the vacuum chamber andthe upper end of the shaft. 22 extends. through abearihg in the top I8. andtintougil-L a. stuhg' box; Z This; stuffing box 2.8, ismerel'yrepresentative of sealing, means that permit. rotation of the. shaft. 2,2 and',A prevent any substantial leakage of air into the vacuum chamber..

The upper endA of; the shaft 22 isconnectedrby a coupling 30 to the armature shaft of a motor 31h This motor is supported from the top I8 of the. vacuum pump; by brackets 34, and itis these brackets that locate the.y motor above the top of. the:- pum-p:v so that when the pump is located in al cellar or sump', andi there is water standing on:V

the oor on certain occasions, a motor 32 is at sufficient elevation above the floor to be above the level or any water that is likely to accumulate or stand on the floor of the cellar or sump, as previously explained.

Each of the pipes 23 of the impeller has the general shape of a spiral helix, the diameter of the convolutions increasing toward the top of the impeller so that the water is urged toward the upper ends of the pipes by centrifugal force as the impeller rotates. The discharge opening at the end of each of the pipes 23 is of very small angular extent compared to the angular extent of the outlet passage around the axis of the vacuum chamber` I I; and as the impeller rotates, the impeller pipes 23 hurl streams of water into the outlet passage in the form of expanding spiral convolutions. These convolutions of the water stream are indicated in Fig. l by the reference character 31, and it is important to have the motor 32 drive the impeller at a speed which is fio-ordinated with the length and cross section of the outlet passage 2I so that there will always be a plurality of convolutions 31 between the inner and outer ends of this outlet passage.

One of the advantages of using two pipes 23 on the impeller is that the pipes face in opposite directions and counterbalance one another around the axis of rotation of the shaft 22. Another advantage in using two or more pipes 23 is that the additional stream of water hurled into the outlet passage by the second pipe makes it possible to have a plurality of convolutions 31 at lower speeds of rotation of the impeller.

Each successive convolution 31 traps some air between it and the preceding convolution. Back pressure against the liquid convolutions 31 causes them to lose velocity as they travel outward along the discharge passage 2 I. As the radial velocity of each convolution decreases, the convolution following it comes closer and compresses the air between the convolutions so that by the time the convolutions are discharged into the separation chamber I6, the air trapped between the convolutions is at substantially atmospheric pressure. This air is left in the chamber I6 as the water falls by gravity into the bottom of the chamber I6, and as the amount of air in the chamber I6 increases, some of it escapes through a vent 40 so that pressure in the chamber I6 can never rise substantially above atmospheric pressure.

The lower ends of the pipes 23 extend downward into the bottom portion of the vessel I and dip into water in this bottom portion of the vessel. The inlet opening at the bottom of each of the pipes 23 is disposed so that it faces in the direction in which the lower ends of the pipes move during rotation of the impeller. This causes the lower open ends of the pipes 23 to act as scoops as they are driven through the water, and the force developed by this scooping action forces the water at least part way up pipes 23 and makes it possible to operate the vacuum pump at higher vacuums and with vacuum chambers of substantial height. When the vacuum pump is to be used for low vacuum heads, it is not necessary to have the lower ends of the pipes 23 face in the direction in which they move as the impeller rotates.

The lower portion of the vacuum chamber II and of the separation chamber I6 comprise reservoirs for holding the hurling water that is used to operate the vacuum pump. The higher pressure in the separation chamber I6 causes water to ow from the separation chamber I6 through an orifice 43 and into the reservoir in the lower part of the vacuum chamber. In order to stop the flow of water from the chamber I6 before the water level drops below the orifice 43, a valve 45 is provided, and this valve G5 closes the orifice t3 whenever the water level in the chamber I6 drops below a predetermined level, that is safely above the orice so as to prevent air from entering the vacuum chamber through the orice.

The valve 45 is operated by a float 36 connected with a bell crank 41. This bell crank 41 rocks about a fulcrum 5S on a bracket secured to the outside of the vessel Ill. The lower end of the bell crank 41 is connected to the valve 45. This leverage connection between the iioat 48 and valve Q5 is shown in its simplest form in the drawing for clearer illustration and is merely representative of motion transmitting connections between the float 46 and valve 45. Although the valve 45 can be operated by a float that is responsive to the water level in the vessel I0, it is preferable t0 have the float in the chamber I6 because this leaves more free space in the vessel I0 for the impeller. With a given quantity of water in the vacuum pump, however, each level of water in the chamber I6 corresponds to a given level of water in the vessel I0.

The pump can be made with various proportions of length to diameter, but it is important to have the outlet passage from the vacuum chamber long enough to contain a plurality of convolutions 31 at every instant. The speed with which the impeller must be driven depends upon the number of discharge outlets of the impeller, as previously explained, and depends also upon the length of the outlet passage from the vacuum chamber and upon the head against which the pump must operate. 1f the length of the outlet passages is reduced, it is necessary to run the impeller faster in order to have a suicient number of convolutions 31 in the outlet passage.

The head against which the pump can operate successifully depends upon the number of convolutions in the outlet passage 31 and upon the centrifugal force with which each successive convolution is hurled into the outlet passage. An increase in centrifugal force can be obtained by increasing the speed of rotation of the impeller; or by making the pump with a larger radius for the impeller and the chamber I I so that the force of the water streams is increased by the greater radius of the circumference about which they travel.

The reservoirs in which the water in held must necessarily be in the lower ends of the vessel I0 and housing I5, but terms of orientation are for the most part relative, and changes and modifications can be made in the illustrated construction without departing from the invention as dened in the claims.

What is claimed is:

l. A vacuum pump comprising vessel enclosing a vacuum chamber, the lower portion of the vacuum chamber comprising a reservoir for liquid, a fixed outlet passage opening through one side of the vessel and having an angular extent around the longitudinal axis of the vessel, an impeller within the chamber, the impeller having an inlet that communicates with the liquid reservoir in the lower portion of the vacuum chamber, a bearing on which the impeller rotates about an axis extending longitudinally of the chamber, a liquid discharge outlet in the impeller and disposed in position to travel a stationaryl around the angular extent of said outlet passage during rotation of the impeller about its axis so as to throw a stream of water into said outlet passage, the angular extent of the discharge outlet of the impeller being substantially lesszthan the angular extent of the outlet passage, and a motor that rotates the impeller at a speed coordinated with the outlet passage length.

' 2. A vacuum pump including a vessel that encloses a vacuum chamber, said chamber having an inlet passage through which air is drawn into the chamber and having an annular outlet passage surrounding the longitudinal axis of the vessel, an impeller located within the vacuum chamber and rotatable about an axis extending longitudinally of the vessel, said impeller having an inlet through which it takes w-ater from a low part of the vacuum chamber and having a discharge outlet of substantially less angular extent than the outlet passage and in position to hurl liquid by centrifugal force into the annular outlet passage in the form of expanding convolutions of a spiral, and a motor that drives the impeller fast enough to keep a plurality of convolutions within the annular passage at all times during the operation of the pump.

3. The vacuum pump described in claim 2 and in which the annular passage has top and bottom walls that converge toward the outer end of said passage.

4. A vacuum pump including a vacuum chamber having a longitudinal axis and an outlet passage which is of substantial angular extent about said axis and of much smaller extent in a direction parallel to said axis, said outlet passage having top and bottom walls that converge toward the outer end of the passage, an impeller in the chamber rotatable about an axis extending longitudinally of the chamber, and a liquid reservoir in the lower portion of the vacuum chamber and into which the impeller extends, said impeller having an inlet in said reserv-oir and said impeller having also a discharge outlet of substantially smaller angular extent than the outlet passage, said discharge outlet being located in position to hurl successive spiral convolutions of liquid into the passage with each successive revolution of the impeller, and a motor that drives the impeller at a predetermined speed which is coordinated with the passage length.

5. A vacuum pump as described in claim 4 with an impeller having a plurality of discharge outlets in position to hurl spiral convolutions of liquid into the outlet passage successively so that Ia plurality of convolutions can be maintained in the passage with lower motor speed.

6. A vacuum pump comprising a stationary cylindrical vessel with its longitudinal axis extending upward, said vessel enclosing a vacuum chamber that has an inlet through which air is drawn and that has a fixed outlet passage of substantial angular extent around the axis of the vessel near the upper end of said vessel, the lower portion of the vacuum chamber comprising a reservoir for liquid, and an impeller located in the vessel and comprising a shaft with its axis extending longitudinally in the cylindrical vessel and with a pipe secured to the shaft for rotation as a unit therewith, said pipe having an upper open end portion extending outward from the center of rotation for discharging liquid by centrifugal force into the outlet passage, and said pipe having a lower open end portion that extends downward into the liquid reservoir in the lower portionl of the vacuum chamber, the upper' and lowerY open ends of said pipe being of sub-1 stantially less radial extent than the outletzpase sage of the vessel, and a motor that drives the impeller at a speed coordinated with the length of" the outlet passage.

7. The vacuum pump described in claim 61 and in which the lower portionV of the pipe has its inlet opening facing in the direction in which the` impeller rotates so that the lower'end ofthe pipe acts as a scoop for driving water into the pipe and for supplying at leastr a part of the force for raising the water upward in the pipe.

8. A vacuum pump comprising a stationary vessel having a bottom portion that rests on a oor or other supporting surface, said vessel enclosing a vacuum chamber that has an inlet conduit for connection with a space that is to be evacuated, said stationary vessel having also a fixed outlet passage from the upper portion of the vacuum chamber, the outlet passage being of substantial angular extent around the longitudinal axis of the chamber, an impeller in the chamber including a shaft that extends through a top wall of the chamber, said impeller having an inlet that communicates with the vacuum chamber in the lower portion of the vacuum chamber, and said impeller also having a discharge outlet of substantially less angular extent than the outlet passage but in position to sweep across the entrance of said outlet passage with each revolution of the impeller, a motor located on top of the vessel, motion transmitting connections between the motor and the upper portion of the vessel including a shaft that extends through the top of the vessel, and a seal at the region where the shaft extends through the top of the vessel for preventing the entrance of air into the vacuum chamber along the shaft.

9. A vacuum pump comprising a vessel having an inner vacuum chamber and an outer separation chamber, surrounding the vacuum chamber for receiving air and Water from the vacuum chamber at substantially atmospheric pressure, the inner vacuum chamber having ya. passage opening into the separation chamber and also having an air inlet passage for communication with a suction line from which air is to be withdrawn, an impeller in the vacuum chamber with an inlet and with a discharge outlet that hurls successive layers of water into the passage through which the vacuum chamber communicates with the separation chamber, a reservoir .at the bottom of each of the chambers for holding water, a valve commanding a passage between the reservoirs in said chambers, and ay valveoperating oat located in one of the chambers and connected with the valve.

10. A vacuum pump comprising an inner vessel enclosing a cylindrical vacuum chamber, an outer vessel surrounding the inner vessel and providing an atmospheric pressure chamber within the outer vessel, the cylindrical chamber having an annular passage around its longitudinal axis and near its upper end and also having an air inlet passage for communication with a suction line from which air is lto be withdrawn, and an impeller in the cylindrical chamber, bearings in which the impeller rotates about an axis extending longitudinally of the cylindrical chamber, said impeller having one or more inlets and having one or more discharge outlets of smaller angular extent than the annular passage and located in position to travel along a path confronting the inner end of the annular passage, a

motor that drives the impeller fast enough to hurl Water from the impeller into the outlet passage in expanding convolutions of a spiral, water reservoirs at the bottoms of both the cylindrical chamber and the atmospheric pressure chamber, a Valve commanding a-n orifice that opens through the wall of the inner vessel between the reservoirs, a float in the reservoir of the atmospheric pressure chamber, and a lever system connecting the float with the valve and movable to open the valve whenever the float rises with the liquid to a predetermined level in the reservoir. HENRY G. SCHAEFER. PHILIP BAUMEISTER.

8 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date '743,163 House Nov. 3, 1903 1,074,043 Breuer Sept. 23, 1913 1,220,000 Radiguer Mar. 20, 191'? 1,312,707 Skidmore Aug. 12, 1919 1,842,940 Jannin Jan. 26, 1932 1,946,524 Crosthwait Feb. 13, 1934 

